inverse of a matrix

Question

in matlab inverse of matlab can be written:

For least squares ( more efficient)

x = A\b.--------------------------------1

But for covariance matrix (Qxx) of unknown paramters(x), I usually do,

Qxx==inv(A) --------------------------2

How I can write it in efficient way like (1)?

Answer 1

You mean something like:

Qxx = A \ eye(size(A));

?

Real question is, what are you doing with the inverse? If you're just remultiplying it by some other vector c then you can just do...

A \ c

instead of Qxx * c